Making white soap



Patented July 21, 1 953 MAKING WHITE SOAP Frank L. Jackson, Cincinnati; and John 0. Bayer, Sharonvilie, Ohio, assignors to The Procter &

Gamble Company, C I ration of Ohio No Drawing.

incinnati, Ohio, a, corpo- Application November 16, 1949, Serial No. 127,756

13 Claims. (Cl. 260409) This invention relates to a new process for jtreating fatty matter to remove color precursors contained therein.

It'particularly relates to the treatment of oils containing color-forming ingredients so that white soaps may be made therefrom. 7

It has been common practice to use oils and fats such as coconut and tallow that are relatively free of pigments or other colored or colorforming materials in the production of white soaps. with caustic soda produce soaps which, in the solid state, are as white or whiter than the original fatty materials in the solid state. The great demand for white soap coupled with the scarcity of such oils and fats has made it necessary to consider the use of less desirable materials that contain colored or color-forming materials, e. g. sunflower, linseed and soybean oils. Oils of this type in either their original or hydrogenated Such fatty materials upon saponification forms, although they may have a color in the solid state comparable with that of the more desirable stocks, e. g. coconut and tallow, produce soaps which in the solid state are highly colored. This high degree of coloration is caused by the presence of color precursors which are colorless or almost colorless materials in the oil that become highly colored, usually red or reddish orange when oxidized in the oil, or assume colors varying in tintfrom pink to dark brown in soaps prepared b saponification of the relatively colorless oil.

Similar reacting materials are present in other oils such as cotttonseed and peanut oil but these oils produce somewhat lighter soaps-of a more yellowish-hue. The removal of these color precursory materials has been most difficult to attain 'since they are very incompletely adsorbed by.

bleaching agents such as activated carbons and earths. Consequently such oils, particularly soybean and linseed oil, have frequently been rejected as soap making materials.

It is an object of this invention to provide a new method for treating oils and fats containing color precursory materials so that white or very light colored soaps can be made therefrom.

It is a further object to provide a method whereby the color precursors normally present in oils, e. g. linseed and soybean, are altered so that they are removed from the oils upon contact with adsorptive bleaching agents. Other objects. of this invention will be apparent in the descriptive matter that follows.

' We include in the terms fatty materials or fatty matter, animal and vegetable oils, fats and waxes, including those of marine origin, and derivatives thereof;

We have discovered that color precursors in the oils and fats can be altered by hydrogenation followed by treatment with chlorites in the presence'of sulfuricacid, and that the thus altered precursor can beremoved by contactwith an adsorption medium, preferably in the presence of a material for neutralizing the free acid in the oil; and that when oils treated in this manner are saponified with alkali the resulting soaps are much lighter than they would have been if the chlorite treatment had been omitted.

The chlorites of various metals can be used in the process of our invention. However, it is obvious that although the chlorites of numerous metals will effect the above mentioned alteration in the precursors, the use of chlorites of certain metals (or even the presence of mere contaminations of metals), e. g. copper, that will promote rancidity or coloration of the fatty matter is to be avoided. When using watersolutions of the chlorites the morereadi'ly water-soluble chlorites a reddish orange color, and soaps prepared therefrom are pink and/or brown due to color devel-, opment in the precursory materials. Before the advent of our discovery that these altered precursors could be removed from the oil by bleaching earths, this color development in the oil was not considered to be of any assistance inthe production of white soaps. It is of further interest that the full value of this invention is obtained only when the three steps of hydrogenation, chlorite treatment, and earth bleaching are performed in the order indicated.

Without wishing to limit our invention to any particular theory, since the. desired results may be obtained by practicing the invention as herein described, the following explanation may be of interest. It is believed that, during the treatment of .oils with chlorites and acids, complex aromatic phenolic compounds are oxidized to highly colored and more readily adsorbable 5 quinoid compounds through the medium of chlorine dioxide that is obtained through the following reaction:

4NaC10z+2H2SO4 4HC102+2N&2SO4 4HC102 2C102+HC103+HC1+H2O This process may be carried out in numerous ways, preferred embodiments of which are described below in detail.

Example 1.A batch of soybean oil that had previously been bleached with 3% of Super Filtrol (an acid activated bleaching earth) was hydrogenated to an I. V. of 65 and filtered through kieselguhr. The Lovibondcolor of the oil (measured on a 5%, column) at this stage was 7 yellow and 1.1 red. The oil was divided into two portions as follows:

(1) The first portion was treated with 0.1% sodium chlorite (as a water solution) plus 0.025% of sulfuric acid (as a 20% solution) for minutes at 100 to 110 C. with constant agitation. During this treatment the oil became reddish orange (Lovibond color-=5 yellow and 28 red). An amount of calcium carbonate slightly in excess of that required to neutralize the acid was then added with 3% of Super Filtrol to the oil and stirred for one hour at 100 to 110 C. The bleaching earth and calcareous material was then removed from the oil by filtration, the final color of the oil being 9 yellow and 1.? red. This first portion of the oil was then mixed with an equal weight of a mixture of equal parts of tallow and coconut oil, converted into kettle soap, crutched, framed, cut, and stamped to form cakes or bars by well known methods. These bars were off-White in color.

(2) The second untreated portion of the oil was mixed with tallow and coconut oil and converted into soap in the same manner. The resulting bars had a decidedly objectionable brownish pink tint.

Reflectance or whiteness measurements of the bars gave the following results:

Soap Whiteness From treated oil 64.3 From untreated oil 51.5

The relative whiteness was determined by meas uring the per cent reflectance of a standard blue light from the soap surface as measured by a Hunter-multipurpose photoelectric reii-ectometer. This instrument is described in Research Paper 1345 by Richard S. Hunter in the Journal of Research of the National Bureau of Standards, page 581, vol. 25, November 1940.

The chlorites of other metals, e. g. chlorites of any of the other alkali metals and of alkaline earth metals can be used with substantially the same results as those obtained with sodium chlorite.

Calcium carbonate is particularly useful as a neutralizing agent in this process, since any excess used can be removed during the filtration along with the insoluble calcium sulfate formed during the process of neutralizing the free acids present in the mixture. The neutralization of the acid, however, can be effected with other alkaline materials, 6. g. barium hydroxide, soda ash, and caustic soda, or can even be omitted. In example 2 no neutralizing agent was used prior to or during the Super Filtrol bleaching. Obviously, however, in this case any residual acid remaining in the stock was neutralized by the caustic soda employed in the saponification of the oil.

Example 2.A batch of soybean oil that had been refined by water washing and also hydroiii . 4:. genated to an I. V. of 68 was oxidized with 0.1% sodium chlorite (as a 20% water solution) in thepresence of 0.025% of sulfuric acid (as a 20% water solution) at to C. for one hour with constant agitation. The color of the oil changedduring the oxidation from a light yellow to a very reddish orange. The oil was then bleached with Super Filtrol as in Example 1. comparison of the soap made from the untreated oil (Lovibond color of oil=5.0 yellow and 1.0 red-5 A," column) with that made from the treated oil (20 yellow and 2.4 red) showed that a very marked improvement in the soap color was obtained by this oil treatment. The soap from the untreated oil was brown in color while that made from the treated oil was almost pure white, showing only a faint trace of pink color.

The usage of fullers earths or bleaching earths for bleaching the chlorite treated oil will vary with the time of contact, temperature, and activityof the earth. Normally 2% to 4% of activated earth such as Super Filtrol gives excellent results; however, the amount may well be varied from 0.5% to 6% or more and, when desired, the oil can be treated with successive batches of ad-' sorptive bleaching agents, thereby effecting econornies in consumption of the bleaching agents. The bleaching can also be carried out in a vacuum, thereby reducingthe darkening effects of atmospheric oxygen on the oil.

Oils such as soybean and linseed are usually hydrogenated prior to being converted to soap, in order to make a firmer soap and one having a greatly reduced tendency to go rancid. We have found that the hydrogenation is used to much greater advantage when it precedes the chlo-. rite oxidation process, and such prior hydrogenation is preferred in the practice of this invention. w If it is carried out after the chlorite oxidation and before the reddish orange or brown mate-..

rials have been removed by bleaching earth, we

ble.

There appears to be no polymerization or resinification of the colored compounds formed during the chlorite treatment such as could account for greater adsorbability after oxidation,

and it would therefore seem that the oxidation alters or reverses the charge on these coloring materials in such a manner that they can be adsorbed on the bleaching earth.

We prefer to use sulfuric acid in the chlorite treatment because of its low cost, its superior performance in this process, and because of the ease with which it can be neutralized with chalk (calcium carbonate) and removed from the oil as.

insoluble calcium sulfate.

Concentrated sulfuric acid can be used in this process, but we havefound that slightly better colors are obtained by using the acid in a dilute form, e. g. in the neighborhood of 20% water solution, thereby obtaining a pH range of about 2 or slightly lower during the chlorite bleaching.

For oils such as soybean we prefer to use about 0.1% of chlorite. in soap colors is obtained With amounts as low as 0.05%, particularly with oils that contain However, marked improvement smaller amounts of materials requiring the oxi-- dative treatment. Larger amounts than 0.1%

can also be used, but care should be .taken not to that of producing white soaps from precursorcontaining fatty matter, the improvement in the fatty matter itself that is obtained by the removal of the color precursory materials is of independent value and utility. It further enhances the ability of the fat or oil to withstand deterioration with aging, particularly with regard to color development.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. The process of treating hydrogenated vegetable fatty materials containing substantially colorless color precursors, which comprises the steps of treating said materials with about 0.1% of a compound of the group consisting of chlorites of alkali metals and alkaline earth metals in water solution in the presence of about 0.025% of sulfuric acid at a temperature in the range. of 100 to 140 C. thereby converting the color precursors into colored materials, and thereafter admixing with the treated fatty matter an alkaline material in amount at least sufficient to neutralize the remaining acid, and bleaching the fatty matter with from 0.5 to 6% of a bleaching earth at a temperature in the range of 100 to 140 C'., and filtering the oil.

2. A process of making white soaps from vegetable fatty matter containing color precursors which normally occur in the fatty matter in a substantially colorless state, which comprises the steps of hydrogenating said fatty matter, treating it with metal chlorites in the presence of sulfuric acid thereby converting the substantially colorless precursors into colored materials, removing such colored materials by contacting the treated fatty matter with an adsorptive bleaching earth, and saponifying the fatty matter to form soap.

3. The process of claim 2 wherein the acid present after the chlorite treatment is neutralized prior to contacting with bleaching earth.

4. The process of claim 2 wherein the neutralizing agent is calcium carbonate.-

5. The process of claim 2 wherein the chlorite used is a member of a group consisting of chlorites of alkali metals and alkaline earth metals.

6. The process of claim 2 wherein the fatty matter is a member of the group consisting of soybean, linseed, and sunflower seed oil.

7. The process of claim 2 wherein the chlorite treating and bleaching operations are conducted at a temperature in the range of 100 to 140C.

8. The process of claim 'I wherein the temperaused is about 0.1% of the weight of the fatty matter.

10. The process of claim 2 wherein at least 0.05% sodium chlorite is used.

11. The process of treating hydrogenated vegetable fatty materials containing substantially colorless color precursors which produce distinct colorations in soaps otherwise made therefrom, which comprises the steps of-treating said materials with about 0.1% of a compound of the group consisting of chlorites of alkalilmetals and alkaline earth metals in water solution in the presence of about 0.025% of sulfuric acid at a temperature inthe range of 100 to140 C. thereby converting the color precursors into distinctly colored materials, and thereafter admixing with the treated fatty matter an alkaline material in amount at least suificient to neutralize the remaining acid, and bleaching the fatty matter with from 0.5% to 6% of a bleaching earth at a temperature in the range of 100 to 140 C., filtering the oil, and saponifying the fatty material to form a white soap.

12. The process of treating hydrogenated soybean oil, which comprises admixing said oil with treating agents consisting of a small amount of sodium chlorite and a small amount of sulfuric acid at a temperature of 85 to 140 C. thereby effecting a distinct coloration in the oil and adding thereto and mixing therewith about 0.5 to 6% of a bleaching earth at a temperature of 100 to 140 C., filtering the oil, and saponifying the oil to form a white soap.

13. The process of treatin hydrogenated fatty materials which produce distinct colorations in soaps otherwise made therefrom, which comprises the steps of treating said materials with about 0.1% of a compound of the group consisting of chlorites of alkali metals and alkaline earth metals in Water solution in the presence of sulfuric acid in amount sufficient to give a pH of about two and slightly under at a temperature in the range of 100 to 140 C., and thereafter admixing with the treated fatty matter an alkaline material in amountat least sufficient to neutralize the remaining acid, and bleaching the fatty matter with from 0.5'to 6% of a bleaching earth at a temperature in the range of to C.,

filtering the oil, and saponifying the fatty matter to form a white soap.

FRANK L. JACKSON. JOHN C. BAYER.

References Cited in the file of this patent UNITED STATES PATENTS Number 

1. THE PROCESS OF TREATING HYDROGENATED VEGETABLE FATTY MATERIALS CONTAINING SUBSTANTIALLY COLORLESS COLOR PRECURSORS, WHICH COMPRISES THE STEPS OF TREATING SAID MATERIALS WITH ABOUT 0.1% OF A COMPOUND OF THE GROUP CONSISTING OF CHLORITES OF ALKALI METALS AND ALKALINE EARTH METALS IN WATER SOLUTION IN THE PRESENCE OF ABOUT 0.025% OF SULFURIC ACID AT A TEMPERATURE IN THE RANGE OF 100 TO 140* C. THEREBY CONVERTING THE COLOR PRECURSORS INTO COLORED MATERIALS, AND THEREAFTER ADMIXING WITH THE TREATED FATTY MATTER AN ALKALINE MATERIAL IN AMOUNT AT LEAST SUFFICIENT TO NEUTRALIZE THE REMAINING ACID, AND BLEACHING THE FATTY MATTER WITH FROM 0.5 TO 6% OF A BLEACHING EARTH AT A TEMPERATURE IN THE RANGE OF 100 TO 140* C., AND FILTERING THE OIL. 